Semiconductor chip packages such as planar lightwave circuits (PLCs) are used in a variety of applications including wavelength division multiplexing (WDM) based optical networks to provide voice, data and broadcast services. PLCs have a waveguide structure in which light from a semiconductor laser diode can propagate, split and recombine. The waveguide structure for guiding light includes a core layer in which light propagates and a cladding layer encompassing the core layer and having an index of refraction greater than that of the core layer. In some cases the refractive index of the core layer is larger than the refractive index of the clad layer by 0.025 and results in total reflection during light transportation. PLCs are used as an optical power distributor, a wavelength splitting/combining filter, an optical switch using a thermo-optic effect, a variable optical attenuator, and a wavelength variable filter. PLCs often have a small device size and are compatible with a semiconductor process. PLC device manufacturers are continually challenged to reduce costs while increasing quality and reliability.